The space shuttle
has provided regular access to orbit since 1981. Here an astronaut is
on an EVA (extra-vehicular activity) repairing a satellite (portion at
upper right) during the STS-51A flight in November 1984. The cargo bay
is used to transport satellites as well as scientific instruments mounted
within the bay, some of which are operated by the crew onboard the spacecraft.
The ever-changing panorama of Earth provides a vivid backdrop to these
operations in orbit. Since 1986 the Soviet Union (now Russia) has maintained
a long-term manned presence in space using the Mir space station as a
base of operations, and the United States is making preparations for a
future international space station.